Data assimilation aims to blend incomplete and inaccurate data with physics-based dynamical models. In the Earth's radiation belts, it is used to reconstruct electron phase space density, and it has become an increasingly important tool for validating our current understanding of radiation belt dynamics, identifying new physical processes, and predicting the near-Earth hazardous radiation environment.
The dataset presents the electron flux reconstructed by assimilating electron flux measurements of the following spacecraft into the 3D Versatile Electron Radiation Belt model (VERB; Shprits et al., 2008, Subbotin and Shprits, 2009):
1. Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS; Blake et al., 2013) and Relativistic Electron Proton Telescope (REPT; Baker et al., 2013), and
2. Geostationary Operational Environmental Satellites (GOES) Magnetospheric Electron Detector (MAGED; Hanser, 2011), and Energetic Proton, Electron, and Alpha Detector (EPEAD; Onsager et al., 1996, Hanser, 2011).
The method employs a split-operator Kalman filter (Shprits et al., 2013). The dataset contains electron flux for the period from 01 October 2012 00:00 UT to 01 October 2016 00:00 UT, organized in monthly files for selected values of electron energies (0.5 MeV, 1 MeV, and 2 MeV) and equatorial pitch angles (20 degree, 50 degree, and 70 degree).
Here, we present an empirical model of the equatorial electron pitch angle distributions, based on the Magnetic Electron Ion Spectrometer (MagEIS) instrument aboard the Van Allen Probes. The model was created for energies from 37 keV up to 2.65 MeV. The model uses the solar wind dynamic pressure as a driving parameter and has a continuous dependence on Lm, magnetic local time and activity. It works for L-shells from 3.05 up around 5.95. For each channel of the MagEIS instrument, there are two files with model coefficients, one for Pdyn <5.5-6 nPa (e.g., “Pijk_246_keV.dat’) , and the second one for very high dynamic pressure values above 5.5 nPa (e.g., “Pijk_246_keV_HIGH.dat’). The script to read both file types is provided (“read_coefs.py”), and the data format is explained in the readme file.
In the near-Earth space, there are a large population of high energy electrons trapped by Earth’s magnetic field. These energetic electrons are trapped in the regions called Earth’s ring current and radiation belts. They are very dynamic and show a very strong dependence on solar wind and geomagnetic conditions. These energetic electrons can be dangerous to satellites in the near-Earth space. Therefore, it is very important to understand the mechanisms which drive the dynamics of these energetic electrons. Wave particle interaction is one of the most important mechanisms. Among the waves that can be encountered by the energetic electrons when they move around our Earth, whistler mode chorus waves can cause both acceleration and the loss of energetic electrons in the Earth's radiation belts and ring current. To quantify the effect of chorus waves on energetic electrons, we calculated the bounce-averaged quasi-linear diffusion coefficients using the chorus wave model developed by Wang et al (2019) and extended to higher latitudes according to Wang and Shprits (2019). Using these diffusion coefficients, we calculated the lifetime of the electrons with an energy range from 1 keV to 2 MeV. In each magnetic local time (MLT), we calculate the lifetime for each energy and L-shell using two different methods according to Shprits et al (2007) and Albert and Shprits (2009). We make the calculated electron lifetime database available here. Please notice that the chorus wave model by Wang et al (2019) is valid when Kp <= 6. If the user wants to use this lifetime database for Kp >6, please be careful and contact the authors.